Symptoms of Potassium Deficiency in Citrus and Methods for Its Prevention and Control
Release Date:
2019-02-15
Potassium deficiency characteristics: 1. Slow growth, few new shoots, small and sparse leaves, and dieback of young branches. Some leaves turn bronze‑colored or exhibit uneven chlorosis. 2. Yellowing of the midribs and lateral veins, with increased susceptibility to sunburn. 2. In severe cases, leaves become twisted and curled, taking on a cupped shape. Fruits show reduced size and thin skin. Correction methods: 1. For soils low in organic matter—such as red soils, red‑yellow soils, light sandy soils, and acidic soils—it is best, when establishing an orchard, to deeply till and incorporate green manure, or to apply additional organic fertilizers, thereby improving soil structure, increasing potassium content and cation exchange capacity, and enhancing overall fertility. 2. For established citrus orchards, adopt a combined approach of chemical and organic fertilization for correction. Organic matter should be thoroughly mixed into the soil, and potassium sulfate should be used as the chemical fertilizer.
Potassium deficiency characteristics
1. Slow growth, few new shoots, small and sparse leaves, with twigs dying back. Some leaves turn bronze-colored or exhibit uneven yellowing. 2. Yellowing of the main and lateral veins, with increased susceptibility to sunburn.
2. In cases of severe potassium deficiency, leaves become twisted and curled, taking on a cup-like shape. Potassium-deficient fruits are small with thin skins.
Correction method
1. For soils low in organic matter—such as red soils, red-yellow soils, light sandy soils, and acidic soils—it is advisable, when establishing an orchard, to deeply till the soil and incorporate green manure, or to apply additional organic fertilizers, in order to improve soil quality, increase potassium content and cation exchange capacity, and enhance soil fertility.
2. For established citrus orchards, corrective measures should be implemented by combining chemical fertilizers with organic amendments. Organic matter should be thoroughly mixed into the soil, and potassium sulfate should be used as the chemical fertilizer; for mature citrus trees, apply 250–500 grams of potassium sulfate per tree annually. It is better to under‑apply than over‑apply, to prevent deficiencies in other nutrients.
3. During the growing period following leaf emergence on new shoots, foliar applications of 0.3%–0.6% potassium dihydrogen phosphate or 0.5%–1.0% potassium nitrate, along with 1%–3% wood ash leachate, yield excellent corrective effects. Potassium sulfate is most effective when applied to the soil; foliar sprays, however, can easily damage leaves and fruits under high-temperature conditions and should be used with caution.
4. During the dry season, mulching with straw, weeds, or crop residues helps reduce soil moisture evaporation; where conditions permit, irrigate the soil promptly to prevent excessive drying.
5. Apply ammonium nitrogen fertilizer sparingly or avoid it altogether to prevent interference with potassium uptake.
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